Wesley S. Hackenberger

High performance single crystal piezoelectrics: applications and issues

Relaxor-based single crystal piezoelectrics began to live up to their promise of providing unprecedented increase of bandwidth, sensitivity and high energy density for advanced piezoelectric transducers and actuator applications. Large size crystals are now available, at reduced cost, for device fabrication and performance tests. The newly gained insights from related investigations opened new opportunities for developing novel piezoelectrics.

Characterization of Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric crystal with enhanced phase transition temperatures

The full set of material constants for relaxor-based ternary single crystals Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIN-PMN-PT) were determined and compared to binary Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMNT) crystals. The Curie temperature for rhombohedral compositions of PIN-PMN-PT was found to be in the range of 160–200 °C with ferroelectric rhombohedral to tetragonal phase transition on the order of 120–130 °C, more than 30 °C higher than that found for PMNT. The piezoelectric coefficients (d33) were in the range of 1100–1500 pC/N, with electromechanical coupling factors (k33) about 89%–92% comparable to PMNT crystals. The coercive field of the ternary crystal was found to be 5.5 kV/cm, double the value of the binary counterparts. The dielectric behavior under varying dc bias exhibited a similar trend as observed in PMNT with a much broader usage temperature range. Together with its enhanced field induced phase transition level, the ternary PIN-PMN-PT crystals are promising candidates for high temperature and...

Phase development and electrical property analysis of pulsed laser deposited Pb(Mg1/3Nb2/3)O3–PbTiO3 (70/30) epitaxial thin films

(001)-oriented heterostructures consisting of LaAlO3 substrates, SrRuO3 bottom electrodes, and Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) (70/30) films were deposited by pulsed laser deposition from Pb-enriched ceramic targets. The epitaxial growth of all layers was confirmed by four-circle x-ray diffraction. Film growth was carried out over a wide range of processing space where substrate temperature, ambient pressure, and laser parameters were varied in order to determine suitable conditions for producing high quality crystals with good electrical properties. In general, strong similarities were observed between thin film and ceramic processing of the same compositions. The associated pyrochlore phase was very difficult to avoid and, in the absence of excess Pb-containing second phases, could only be done at very high temperatures and high oxygen/ozone pressures for films on LaAlO3 substrates. When deposited at temperatures below approximately 640 °C, PMN-PT films grown from lead-enriched targets exhibited depres...

Electromechanical characterization of Pb(In0.5Nb0.5)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 crystals as a function of crystallographic orientation and temperature

Relaxor based Pb(In0.5Nb0.5)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 ternary single crystals (PIN-PMN-PT) were reported to have broader temperature usage range (TR-T) and comparable piezoelectric properties to Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMNT) crystals. In this work, the orientation dependent dielectric, piezoelectric and electromechanical properties for PIN-PMN-PT crystals were investigated along ⟨001⟩ and ⟨110⟩ directions. The electromechanical couplings k33 and k32 for ⟨110⟩ poled crystals were found to be 0.91 and 0.91, respectively, with piezoelectric coefficients d33 and d32 on the order of 925 and −1420 pC/N. Of particular significance was the mechanical quality factor Q33 for ⟨110⟩ oriented crystals, which was found to be ≥500, much higher than the Q values of ⟨001⟩ oriented relaxor-PT crystals (Q∼70–200). The temperature dependence of the piezoelectric properties exhibited good temperature stability up to their ferroelectric phase transition TR-T∼125 °C, indicating ⟨001⟩ and ⟨110⟩ oriented PIN-PMN-PT are promisin...

Electromechanical characterization of crystals as a function of crystallographic orientation and temperature

Relaxor based Pb(In0.5Nb0.5)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 ternary single crystals (PIN-PMN-PT) were reported to have broader temperature usage range (TR-T) and comparable piezoelectric properties to Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMNT) crystals. In this work, the orientation dependent dielectric, piezoelectric and electromechanical properties for PIN-PMN-PT crystals were investigated along ⟨001⟩ and ⟨110⟩ directions. The electromechanical couplings k33 and k32 for ⟨110⟩ poled crystals were found to be 0.91 and 0.91, respectively, with piezoelectric coefficients d33 and d32 on the order of 925 and −1420 pC/N. Of particular significance was the mechanical quality factor Q33 for ⟨110⟩ oriented crystals, which was found to be ≥500, much higher than the Q values of ⟨001⟩ oriented relaxor-PT crystals (Q∼70–200). The temperature dependence of the piezoelectric properties exhibited good temperature stability up to their ferroelectric phase transition TR-T∼125 °C, indicating ⟨001⟩ and ⟨110⟩ oriented PIN-PMN-PT are promisin...

5I-1 Microfabrication of Piezoelectric Composite Ultrasound Transducers (PC-MUT)

In this paper a piezoelectric composite based micromachined ultrasound transducer (PC-MUT) fabrication technology is presented. PMN-PT single crystal posts with side length of 14 mum and height of > 60 mum were fabricated using a deep dry etching method. High frequency (20-50 MHz) PMN-PT single crystal/epoxy 1-3 composites were prepared and the electromechanical coupling coefficient of the composites was ~0.72. Prototype 40 MHz ultrasound transducers showed promising sensitivity and bandwidth

A small, linear, piezoelectric ultrasonic cryomotor

A small, linear-type, piezoelectric ultrasonic cryomotor has been developed for precision positioning at extremely low temperatures (⩾−200°C). This cryomotor consists of a pair of Pb(Mg1∕3Nb2∕3)O3−PbTiO3 single crystal stacks, which are piezoelectrically excited into the rotating third-bending mode of the cryomotor stator’s center, which in turn drives a contacted slider into linear motion via frictional forces. The performance characteristics achieved by the cryomotor are: (i) a maximum linear speed of >50mm∕s; (ii) a stroke of >10mm; (iii) a driving force of >0.2N; (iv) a response time of ∼29ms; and (v) a step resolution of ∼20nm.

Nonlinear dielectric ceramics and their applications to capacitors and tunable dielectrics

Nonlinear ceramics that provide the basis for high-energy-density and high-temperature capacitors, as well as tunable microwave dielectrics, and their applications are discussed in this article.

Relaxor-based ferroelectric single crystals for electromechanical actuators

The piezoelectric properties of relaxor based ferroelectric single crystals, such as Pb(Zn1/3Nb2/3)O3 - PbTiO3 (PZN-PT) and Pb(Mg1/3Nb2/3)O3 - PbTiO3 (PMN- PT) were investigated for electromechanical actuators. In contrast to polycrystalline materials such as Pb(Zr,Ti)O3 (PZTs), morphotropic phase boundary compositions were not essential for high piezoelectric strain. Piezoelectric coefficients (d33s) > 2500 pC/N and subsequent strain levels up to > 0.6% with minimal hysteresis were observed. Crystallographically, high strains are achieved for <001> oriented rhombohedral crystals, though <111> is the polar direction. Ultrahigh strain levels up to 1.7%, an order of magnitude larger than those available from conventional piezoelectric and electrostrictive ceramics could be achieved, being related to an E-field induced phase transformation. Strain vs. E-field behavior under external stress was also much superior to that of conventional piezoelectric ceramics. High electromechanical coupling (k33) > 90% and low dielectric loss <1%, along with large strain make these crystals promising candidates for high performance solid state actuators.

Multilayer ceramic capacitors based on relaxor BaTiO3-Bi(Zn1/2Ti1/2)O3 for temperature stable and high energy density capacitor applications

The need for miniaturization without compromising cost and performance continues to motivate research in advanced capacitor devices. In this report, multilayer ceramic capacitors based on relaxor BaTiO3-Bi(Zn1/2Ti1/2)O3 (BT-BZT) were fabricated and characterized. In bulk ceramic embodiments, BT-BZT has been shown to exhibit relative permittivities greater than 1000, high resistivities (ρ > 1 GΩ-cm at 300 °C), and negligible saturation up to fields as high as 150 kV/cm. Multilayer capacitor embodiments were fabricated and found to exhibit similar dielectric and resistivity properties. The energy density for the multilayer ceramics reached values of ∼2.8 J/cm3 at room temperature at an applied electric field of ∼330 kV/cm. This represents a significant improvement compared to commercially available multilayer capacitors. The dielectric properties were also found to be stable over a wide range of temperatures with a temperature coefficient of approximately −2000 ppm/K measured from 50 to 350 °C, an important...